Thread-cutter for sewing-machines.



(No Model.)

R. W. THOMSON;

THREAD CUTTER FOR SEWING MACHINES.

(Application filed Oct. 15, 1900. Renewed Sept. 25, 190 1.)

2 SheetsSheot I.

11-1: uonms PEIERS 00., PHDTO-LITNO.. wAsHmr-Ycrx o. c.

.m.'s9'|,s7s. Patented lan. '2l, I902.

R. w. THOMSON.

THREAD CUTTER FOB SEWING MACHINES.

(Application filed'Oct. 15, 1900. Benewad Sept. 25, 1901 (No Model.) 2Sheets-Shee't 2.

munmnlm 1.1

iii/M "cams przns co moruuma. WASHINGTON. o. e

. cause the needle descends almost instantane UNITED STATES PATENTOFFICE.

ROBERT W. THOMSON, OF LYNN, MASSACHUSETTS, ASSIGNOR, BY MESNEASSIGNMENTS, TO PHILADELPHIA EARRING MACHINE COMPANY, OF CAMDEN, NEWJERSEY, A CORPORATION OF NEWV JERSEY. I

THREAD-CUTTER FOR SEWING-MACHINES.

SPECIFICATION formingpart of Letters Patent No. 691,67 6,- dated January21, 1902.

Application filed October 15, 1900. Renewed September 25, 1901. SerialNo. 76,531. on; model.)

To aZZ whom it may concern.-

Be it known that 1, ROBERT W. THOMSON, a citizen of the UnitedStates,residing at Lynn, in the county of Essex and State ofMassachusetts, have invented a new and useful Improvement inThread-Cutting Mechanism for Sewing-Machines, of which the following isa specification.

Myinvention is an improvement upon sewing-machines of the class whereina threadcutting mechanism operates automatically and simultaneously withthe stopping of the machine to cut the threads, and thus prepare themachine for a succeeding operation. An example of machines of this classis found in the sewing-machine described in Letters Patent of the UnitedStates No. 545,391, issued tome August 27, 1895, and further developmentof such machines is illustrated in Letters Patent of the United StatesNo. 660,130, issued to me October 23, 1900. The successful and accurateoperation of such machines requires the cutting-blades to be locatedvery close to the under side of the throat-plate of the machine and topass close to the needlehole, in some instances to pass directly underthe needle-hole in the path of the needle. When the cutting mechanism isin proper condition, the retracting-spring connected therewith may berelied on to retract the cutterblade from the immediate vicinity of theneedle-hole; but when this mechanism is slightly gummed, or if a pieceof thread gets caught in the blade and retards the retractile movement,there is serious liability to damage, be-

ously upon restarting the machine.

My invention presently to be described provides positive means formoving the threadcutter out of harms way when the machine is started.

In the drawings, Figure 1 is a side view of a machine of the characterdescribed with my improvement attached. Fig. 2 is a view in perspectiveof the cutter-retracting mechanism with the machine-frame indicated by.

dotted lines. Fig.3 is a detail of a portion of the mechanism shown inFig. 2, and Figs. 4: and 5 are illustrations of parts of the automaticstop mechanism.

The stopping and starting mechanism and the connected parts whichactuate the cutter when the machine is stopped are for the sake ofbrevity in description here shown as sub-v stantially the same as thoseof the machine described in my aforesaid Patent No. 660,130 and arelettered in the drawings as in the drawings of the said patent. Themachinebed 1, .arm 2, needle-shaft N, throat-plate P, cutter and cutterconnections O,shippermechanism S, starting-lever and connectionsAandcutter-actuating systems L and M are substantially as shown in thesaid'PatentNo. 660,130

and operate in substantially the same way upon the stopping of themachine.

I have shown herein a machine which operates through a definite stitchcycle determined by the cam O, journaled at 0 which is driven by theWorm O on the needle-shaft N and which controls the movements of thecloth-holding clamp. The stitch cycle is completed by a singlerevolution of the cam O,

and upon the completion of each revolution of the cam the machine isautomatically stopped. Reference to my Patent No. 545,391 willsufficiently explain the relationships of working parts by which a cam,such as 0, controls the stitch-forming mechanism.

Whenby the depression of the starting-lever a a the shipper-fork 8 movesthe belt from loose pulley p? to fast pulley p, the shipper-block spivoted at is moved against the shipper-spring (not herein shown) to aposition where the spring-actuated shipperdetent H (see Figs. 4 and 5for details) catches and holds the shipper-block s byits hook h So longas this condition is maintained the machine must run. As the rotation ofthe cam O nears its completion the tripper-dog 15, secured tothe backside of the cam 0, Figs. 4 and 5, crowds in the end h of theshipperdetent and releases the shipper-block s from the hook h Fig. 4.The shipper=spring thereupon throws the belt back to the loose pulley,

and only the momentum of the working parts of the machine remains tocause continuance of movement. At the moment when the shipcut No.660,130, and the lever system M gives the cutter its final movement.chine rests, with the block 0 and toe r in contact and the cutter-bladeconsequently advanced and in or near the path of the needle.

In order to insure positive retraction of the cutter before the initialdescent of the needle in the next sewing operation, I provide acutter-retractor system, which is embodied in the mechanism now to bedescribed.

The train of mechanism consists of a rod or plunger W, looselysupportedin holes 10* w made in the machine neck and bed, respectively. The upperend 10' of the rod V is rounded and adapted to make operative contactwith the cam U, which is secured to the needle-shaft N. The lower end ofrod W is operatively connected with the cutter-lever by means of abell-crank lever 10" 10 pivoted at w and jointed to the rod W at w. Thearm to of the bell-crank lever makes contact with the cutter-lever, or,if necessitated by the location of the cutter-lever, with anextension-arm, as c, which is preferably adjustable on the cutter-lever,as at c.

When the machine is in operation and before the cutter-actuatingmechanism is in play, the stress of the spring 0 throws the end 0 of thecutter-lever outward, and thus permits the rod V to fall slightly. Theproportions of the parts described are such that when the rod W is inits lowest position during the operation of the machine the camU rotatesidly, its high side a just missing the end to of the rod WV. When,however, the machine stops, the action of the block 0 on the cam 0through the connections heretofore described throws the cutter-lever ende inward and lifts the rod W at the same time that it gives thecutter-blade its initial movement. The cam U is so proportioned that itslow side a is over the rod W when the latter is lifted by the action ofthe block 0'; but at this point the machine stops and the parts are leftas shown in Figs. 1 and 2.

When the machine is again started, the first rotation or partialrotation of the needle-shaft N in the direction indicated by the arrow,Fig. 2, brings the high side a of the cam U down on the end 20 of therod N and positively throws the cutter-lever over, retracting thecutter-blade from the position of danger. The proportions of the cam Uand the connecting mechanism are such that positive retraction of thecutter is inevitable before the needle descends through thethroat-plate.

It is to be observed that the positive depression of the rod W andmovement of the cutter-lever take place-before the toe r of the leversystem L is freed from contact with the block 0. If all the parts of thelever system L were rigid, the forcible depression of the rod W wouldinvolve breakage somewhere. This is provided for by the insertion of anelastic member in the lever system L. The specific structure by whichthis is accomplished is shown in detail in Fig. 3. A stud Then the manis secured to the lever end Z and bored out at n" and n to receive thetoe r, stem 1', and spring r". A collar 1' and binder-screw r serve tosecure the stem r at any desired point of adjustment.

The spring 0' is a stiff one, sufficiently so to render the toe rsubstantially rigid while the cutter-actuating movements are being made.In response to the forcible action of the cam U and rod Vt the spring 7'is compelled to yield and permits the positive retractile move ment ofthe cutter to take place without injury to any part of the machine. Thefirst complete revolution of the shaft N carries the cam 0 forward andwithdraws the block 0 from the toe r, so that the cam U on its nextrevolution rotates idly, the rod W having dropped out of range by reasonof the relaxed condition of the connected parts.

If the character of the machine permits the employment of a block ooranalogous device and a toe r or its equivalent, so nicely proportionedand adjusted that the initial movement of the machine removes theseparts from contact relationship before the retractor mechanism comesinto operation, the clastic member may be omitted; but in most instancessome such yielding part as that described will be found desirable. It isto be observed, also, that if the spring 0 should be broken or shouldnot be attached to its anchorage in the proper manner the cam U will atany time during the operation of the machine guard against accidentaldisplacement of the cutter. The high side of the cam U travels over therod W before and to some extent during the descent of the needle.

The above described positive cutterretracting mechanism is adapted foruse on machines of the character described in my aforesaid Patent No.660,130, as well as on machines wherein a pattern-cam, such as the camO, is employed to determine the character and duration of the stitchcycle.

The peculiar structure and operation of the machine shown in my saidpatent render the presence of an elastic member in the lever system Lunnecessary.

From the foregoing description it will be observed that the presentimprovement relates more particularly to the thread-cutters in which acutting or severing member is arranged and adapted in performing itsnormal function to cross the line of reciprocation of the needle whilethe latter is raised and that its essential feature consists in thecombination, with means for actuating such cutting or severing member,of means independent thereof for positively insuring the retraction ofthe said member before the succeeding descent of the needle, and thatthe specific character of the said retracting means and the actuatingdevice therefor are not, therefore, material parts of the improvement.

What I claim, and desire to secure by Letters Patent, is

i. In a sewing-machine of the character indicated, wherein a stop-motionand threadcutting mechanism are associated, the combination of athread-cutting knife, situated in close proximity to the n eedle-paththrough the throat-plate and movable across said needlepath, acutter-retractor operatively connected with the cutter and so timed withrelation I to the vibrations of the needle-bar that the cutting-knife ispositively automatically retracted upon starting the machine, andwithdrawn from the needle-path before the needle descends through thethroat-plate.

2. In a sewing-machine of the character indicated, wherein a stop motionand threadcutting mechanism are associated, the combination with athread'cntter situated in'close proximity to the needle path through thethroat-plate and movable across saidneedlepath, ofa cutter-actuatorconsisting of a positively-driven train of mechanism of which one partis an, elastic member,connectionsbetween the actuator and the cutter, acutter-retractor, connections therewith to the cutter, mechancuttingmechanism are associated, the combi- Y nation of a cam 'securedto theneedle-shaft,

cutter-retracting mechanism connected at one end with thecutte'r'mechanism and at the other end in operative conjunction with thecam, so that the cam operates on the retracting mechanism when thecutter and its connections are in cutting position.

4. In a'sewing-machine of the character indicated, wherein a stop-motionand threadcutting mechanism are associated, the combination ofcutter-actuating devices and cutterretracting mechanism connected withthe cutter, a cam secured to the machine-shaft, the cam andcutter-retracting mechanism being 7 so proportioned and disposed thatthe cutterretracting mechanism is advanced into operative conjunctionwith the cam when the cutter-actuating devices act to operate thecutter, and is withdrawn from said operative conjunction when thecutter-actuating devices are idle and the cutter retracted.

5. In a sewing-machine of the character indicated, wherein a stop-motionand threadcutting mechanism are associated, the combination of acutter-actuator provided with an elastic contact member, connectionsbetween the actuator and the cutter, a cutter-lever, a cutter-retractorcomprising a retractor-lever in contact with the cutterlever andconnected with an operating-rod, a cam on the machine-shaft, the cam androd so proportioned and disposed as to make contact with each other whenthe machine is started and the cutter is in the position de-' terminedby the operation of, the actuator.

6. In a sewing-machine of the character indicated,the combination with athread-cutting device, of means foractuating the same to cut the thread,and positively-actuated means independent thereof and actingautomatically to insure the return of said thread-cutting device toinitial or inoperative position before the beginning of the succeedingstitch.

7. In a sewing-machine of the'eharacterindic'ated, the combination withstitch-forming devices including a reciprocating needle, and t athread-cutting device with means for actnating it, of means independentof said actuating means whereby said threadcuttin g device is positivelyprevented from remaining in cutting position when the needle descendsbelow the work-plate.

8'. In a sewing-machine of the character indicated, the combination withthe stitch-form'- ing mechanism, and a thread cutter with means forretracting said cutter, and positively-actuated means for insuring theretractionfof said cutter before a predetermined stage of the operationof the stitch-forming mechanism.

9.. In a sewing-machine of the character indicated, the combination'withstitch-forming mechanism including a' reciprocation needle, 7

a thread-cutting knife or cutter movable forpositively actuating it, ofa spring 7 transversely of the line'of reciprocation ofsaid needle, andmeans for positively actuating said cutter while the needle is elevatedabove the work-plate, of means for positively insuring the retraction ofthecutter before the succeeding'descent of the needle.

10. In a sewing-machine of the character indicated, the combination withstitch-forming mechanism including a reciprocating needle-bar and needleand means for actuating the same, of a thread-cutter and means foractuating it to sever the thread while the needle is elevated above thework-plate, and means connected directly with the needle-baractuating,devices but independently of the needle-bar for positively insuring theretraction of the thread-cutter while the needle is still elevated abovethe work-plate.

11. In a sewing-machine of'the character indicated, wherein astop-motion and threadcutting mechanism are associated, the combinationwith the thread-cutter arranged and adapted to operate across the lineof reciprocation of the needle, of a cutter-retractor operativelyconnected with the cutting mechanism, and'means whereby the retractor ispositively automatically actuated upon starting the machine.

Signed by me at Boston, Massachusetts, this 12th day of October, 1900.

ROBERT W. THOMSON,

Witnesses:

E. T. GRoLL, F. S. I-IARTNETT.

